Like ISO 9000, ISO 14000 is a family of standards put forward by the International Organization for Standardization. ISO 14000 deals with environmental management, that is, how companies minimize harmful effects on the environment.

ISO 14000 is concerned with how a company goes about its work (the process, not the product). The idea is that the way a company manages its processes has an effect on the end product. It influences whether or not everything has been done to ensure that a product has the least amount of impact on the environment through its production and disposal, by pollution or by depleting natural resources.

As with ISO 9000, there is no such thing as "ISO 14000 Certification", or an "ISO 14000 Certificate", and to advertise as such is wrong. ISO audits are done by private agencies, independant of the actual ISO. ISO simply publicizes the set of standards, and an audit is not required for you to implement ISO 14000 standards at your place of work.